Creating a new group under contacts (or People)

I  am trying to create a new group under contacts. I followed the advice from Kathleen Collins: I went to the People window, to the toolbar at top, clocked on Manage, then on Manage groups. I was getting excited because so far, so good. After that , no plus+ sign appeared or rather, there is a + sign in a circle at the top (just to the left of "New", but it is greyed out and won't allow me to click on it. Maybe this is not the correct + sign anyway. What is wrong?  I use Firefox, maybe I need to use Explorer in order to do this? Thanks for any advice you can give. Now frustrated and getting desperate.